1. Substitution by molecules in which one atom carries a free doublet

1.1 Phosphines

The discussion in the article on the bond between a metal and a CO molecule shows that donating the carbon doublet is the first piece of data. Logically, the idea of substitution immediately comes to mind, as it should be enough to find a Lewis base and make it work. However, neither ammonia nor an amine reacts with carbonyl iron. The second reason for this inertia is that these molecules are unable to accept in return due to a lack of suitable orbitals. If a molecule capable of accepting in return were brought into play, the reaction would have to take place.

A substituted phosphine PR ₃ should do the trick. In fact, phosphorus, unlike nitrogen, has empty t _...